Information, work, and heat in small systems

大约150年前，詹姆斯·克拉克（James Clerk）麦克斯韦（Maxwell）首次提出了这样一个问题：当一个“手指整洁的生物”--一个魔鬼--利用信息从热中提取有用的能量（功）时，会发生什么？热力学第二定律应该禁止这种情况，但怎么做呢？这个问题困扰着物理学家，并引发了长达一个多世纪的争论。 从2008年开始，我的实验室开发了一种新技术，用于创建和研究这种麦克斯韦恶魔以及收集和使用相关信息的相关设备。这个反馈陷阱让我们把一个微米级的小珠子放在一个我们可以随意设计形状的电势中。这一技术进步在热力学、非平衡统计物理学、信息论和控制论的交叉领域带来了重要的科学应用，特别是2014年的一项权威性测量证实了一个60年前的假设：麦克斯韦恶魔需要擦除信息，而擦除信息需要消耗获得的能量。未来五年，我的研究计划将集中在三组项目上：1。异常冷却和加热。 我们最近使用反馈陷阱来证明，在相同条件下，热系统有时会比热系统冷却得更快（“Mpemba效应”）。在此基础上，我们将研究最近提出的一个非稳态加热方案（逆Mpemba效应）和相关问题。 2.信息与热力学实验。 我们将继续研究信息引擎，总的目标是将麦克斯韦恶魔从提出悖论的思想实验转变为基本热力学极限的实验说明，再转变为执行有用任务的实用设备。我们将优化基本计算操作（位擦除，逻辑门）在有限速率下运行时的成本，并研究信息发挥作用的新问题，例如稳定不稳定系统所需的最小功率。3.单电池中的热流。 我们将开发新的仪器来研究单个生物细胞的产热。长期的动机是创造一种新的工具来理解细胞代谢的动力学--在单细胞水平上营养物质是如何被消耗的。短期目标是解决一个惊人的科学差异，即预测和测量的细胞内温度变化之间的“105差距”。前两个项目直接扩展了我小组以前（非常成功）的工作。第三个是一个新的方向，有可能创造一个新的领域（单细胞量热法），并解决我们这个时代杰出的科学难题之一。 上述问题是我们理解生物学和生命以及小规模工程的基础。他们将激励和帮助培养新一代的HQP，在加拿大和超越。

Nearly 150 years ago, James Clerk Maxwell first asked what happens when a "neat-fingered being"-a demon-takes advantage of information to extract useful energy (work) from heat. The Second Law of Thermodynamics should forbid this, but how? The question galled physicists and provoked debate for well over a century. Starting in 2008, my lab developed a new technique for creating and studying such Maxwell demons and related devices for gathering and using relevant information. This feedback trap lets us place a small, micron-scale bead in a potential whose form we can design, essentially at will. This technological advance has led to important scientific applications at the intersection of thermodynamics, nonequilibrium statistical physics, information theory, and control theory, notably a definitive measurement in 2014 that confirms a 60-year-old hypothesis: that Maxwell demons need to erase information and that erasing information requires dissipating as much energy as is gained. The next five years for my research program will focus on three groups of projects: 1. Anomalous cooling and heating.  We recently used our feedback trap to show that a hot system can sometimes cool more quickly than a warm system under identical conditions ("Mpemba effect"). Building on this success, we will investigate a recently proposed anomalous-heating scenario (inverse Mpemba effect) and related questions. 2. Experiments on information and thermodynamics.  We will continue work on information engines, with the overall goal of transforming Maxwell demons from thought experiments raising paradoxes to experimental illustrations of fundamental thermodynamic limits to practical devices that carry out useful tasks. We will optimize the costs of basic computational operations (bit erasure, logic gates) when operated at finite rates and look at new problems where information plays a role, such as the minimum power needed to stabilize an unstable system. 3. Heat flow in single cells.   We will develop new instrumentation for studying heat production from single biological cells. The longer-term motivation is to create a new tool for understanding the dynamics of cellular metabolism-how nutrients are consumed at the single-cell level. The shorter-term goal is to resolve a striking scientific discrepancy, the "105 gap" between predicted and measured intracellular temperature variations. The first two projects directly extend previous (very successful) work in my group. The third is a new direction, with the potential to create a new field (single-cell calorimetry) and resolve one of the outstanding scientific puzzles of our time. The above questions are ones that underlie our understanding of biology and life, as well as engineering at small scales. They will inspire and help train a new generation of HQP, in Canada and beyond.